The present invention relates to improvements in cases containing a recording tape wound on two reels and able to pass in one direction or the other in front of an aperture, on the other side of which is located a recording and/or reading head when such a case in mounted in the apparatus provided with this head. Cases of this type are generally known as "minicassettes" and are called by this name hereafter.
There are numerous types of minicassettes currently in existence. They all comprise a casing body and a cover fitting one in the other and provided internally with means, produced by molding, for mounting the reels so that they may rotate, guiding the tape in a rectilinear manner in front of the aforesaid head and pressing this tape against the latter.
Until recent years, a major factor in the selling of minicassettes was the lowest possible manufacturing cost and, within this framework, the best possible operation as well as convenient and rapid loading of the tape into the cassette.
There is no doubt that it is difficult to reconcile these various requirements.
Thus, in order to reduce the cost price, cheap plastic materials were used which did not have the desirable rigidity for preventing deformations which are liable to jeopardize the quality of operation.
For this same purpose, attempts have been made to reduce the number of components which are limited to only two parts: a casing body and a cover. This produces difficulties as regards the production of molds and more specifically the passage for the tape. In fact, as regards this latter part, the mold has to be produced by erosion which is bad as regards the smoothness of the sliding surfaces; in addition, owing to the height of the thin projecting parts defining this passage, a slight clearance must be allowed in order that stripping is possible, which is clearly detrimental to the perpendicularity of said passage and consequently to the guiding of the tape in front of the recording and reading head; moreover, since these thin projecting parts are fragile, it is inevitable that now and then certain of them break and if this is not noticed immediately, the parts molded subsequent thereto which are without them can only be rejected; furthermore, the decrease in the cost price due to the limitation of the number of parts is not as considerable as one could have hoped, because, given the extreme complexity of the mold, the cost of the latter is relatively great and one thus abandons producing as many of them as the series of minicassettes to be produced would require, which has the result of increasing their daily production period and of accepting delivery difficulties which may result from inevitable breakdowns. Finally, loading of the tape into the casing is made very difficult by the narrow passage which exists between the tape-guide and the strips protecting the front face in which is provided the aperture for the passage of the aforesaid head.
The preceding explanation shows that a substantial decrease in the cost price is thus obtained, but that the operation of the minicassette, if satisfactory for customary applications, is nevertheless imperfect for new applications explained hereafter.
On the other hand, a desire for better sliding and correct guidance of the tape as well as constant tension, which are prerequisites for good winding of the tape on the spools, leads to the production of various additional systems using bosses, rollers, guides, etc., but which, for reasons already explained, do not always make it possible to obtain the operation required for these new applications.
In fact, the use of the minicassette has recently been extended to recording data (for example on cash registers in super-markets) and for the processing of this data in a computer (in particular records of stocks and supplies). Now, within this framework, the primordial quality desired is the perfection of operation of the minicassette, the cost price, although constituting an important factor in the commercial success, thus being relegated to the background. The quality of operation relates to the sliding of the tape, its correct guidance and its constant tension particularly in the rectilinear part of its passage opposite the recording head, and its constant travelling speed as well as its high rewinding speed without damage.
However, such quality of operation cannot be obtained with known minicassettes.